Embodiments relate to a light emitting device, a light emitting device package, and a lighting system.
In light emitting devices, P-N junction diodes having the properties of converting electrical energy into light energy may be formed by combining group III and V elements on the periodic table. Light emitting devices may realize various colors by controlling the composition ratio of compound semiconductors.
Nitride semiconductors are attracting much attention in the fields of optical devices and high-power electronic devices because of their high thermal stability and wide band gap energy. In particular, blue light emitting devices, green light emitting devices, and UV light emitting devices, which use nitride semiconductors have been commercialized and are widely used.
According to related art, a passivation layer is disposed on a side surface of a light emitting device. When a single-layered passivation layer having the same refractive index is disposed on a side surface and a top surface of the light emitting device, it is difficult to obtain an optimized light output. This is because a reflective index layer satisfying an anti-reflection coating condition is disposed on a side surface and an optimized reflective index layer on the top surface is changed according to a period of a light extraction pattern.
Since diffraction efficiency of the light extraction pattern depends on a refractive index at an interface, a refractive index of the passivation layer filling the pattern may become an important parameter.